I posted about the same thing a couple of days ago because I've been getting period pains on and off quite badly for a while now and from the replies I think it is normal.
I came across an article yesterday about it too and apparently it could be caused by the babies head engaging or your cervix starting to soften.
I'll get horrible period like pain a couple times a week and the days that I do I get them several times that day before going away. Hope your feeling better.